Method of making a molded applique product

ABSTRACT

A method of making a molded applique product. A printed applique substrate is formed into a three dimensional shape and placed into a mold whereupon a molten resin is injected into the mold cavity space located behind the formed substrate.

FIELD OF THE INVENTION

This invention relates to a method of making molded applique products ofthe type made of synthetic resins having printing on a surface thereofand made by a molding process. Products of this type are used, by way ofexample, to make automobile instrument panels.

DESCRIPTION OF THE PRIOR ART

Products of the indicated type have been made for many years by a methodknown in the art as an in-mold decorating process. This process, whichhas been in use since at least as early as 1972, was used to produceprinted parts on polystyrene and polypropylene sheets that were, afterprinting, die cut and sent to injection molders to be in-molded into afinished product. By way of example, some of these products were plasticlunch boxes, pitchers and canisters. In this process, the overlays orin-mold decoratives were produced by offset printing and/or screenprinting, and the parts were flat and were held into the mold with astatic charge. Because the overlays or in-mold decoratives did notcontain complete (100 per cent) ink coverage, it was possible to printon the rear surface of these parts and still have the molten plasticmaterial fused to the rear surface of the plastic substrate, thusleaving a layer of plastic film on the outside to protect the graphics.In this process, the gating of the mold had to be such that theintroduction of the plastic took place where there was no ink, since anyink present in this area would tend to move or distort. The bonding inthis case would only take place between the clear plastic area of theoverlay and the molding compound itself.

A molding method essentially the same as the in-mold decorating processdescribed above is disclosed in U.S. Pat. No. 4,917,927. The patentclaims novelty in the printing step wherein a synthetic resin sheet hasan ink film applied to at least one side of the resin sheet wherein theink film comprises one or more layers, each of which has a specificminimum thickness. The patent states that by this inking process that itis possible to produce a backlighting product. Backlighting products arewell known in the art and are capable of making a pictorial imageprinted thereon look bright when viewed from the front if light is shonefrom the rear of the product. Products of this type are used to makeautomobile instrument panels. The patent discloses the printing on aflat resin sheet which is placed into a die into which a moltensynthetic resin is injected pursuant to the in-mold technique discussedabove.

The prior art techniques were not suitable for making a threedimensional applique of the type shown in FIG. 3 of the drawings. Infact, those skilled in the art believed it would not be possible toobtain the shape and configuration of this type while at the same timeproviding an acceptable decorative presentation. It was believed thatduring the in-mold process of the prior art the product would bedeformed and thereby harm the decorative presentation.

SUMMARY OF THE INVENTION

It is the general object of the invention to provide a method of makingapplique products of the type made of synthetic resins and havingprinting thereon by a molding process to produce a three dimensionalproduct having a shape including protruding portions, concave portions,or the like.

The general object of the invention is achieved by a method comprisingthe steps of:

(1) providing a flat substrate having a minimum of 0.020 inchesthickness and being made of a clear polycarbonate;

(2) printing on the front surface of said substrate using a formableink;

(3) pre-cutting the printed substrate to establish registration holesfor forming tool, this cutting step being performed, for example, by diecutting with a steel rule die;

(4) forming the printed substrate into a three dimensional shape,preferably by a cold forming process to thereby reduce the internalstress from the internal form;

(5) providing a mold having a first surface of the same configuration assaid formed substrate;

(6) die cutting the formed substrate so that it fits to the moldingsurface with minimal interference and such that the part can be placedin the die by reason of its configuration; and

(7) placing the formed substrate into the mold against said first moldsurface and injecting a clear molten polycarbonate resin into the moldcavity space located behind the formed substrate, said molding stepbeing achieved by introducing a molten polycarbonate directly behind theformed substrate through a plurality of gates, said gates being arrangedso that each gate does not supply molten resin to an area greater thantwo square inches.

The above process produces a one-piece, permanently bonded appliqueproduct having the three dimensional shaped configuration of the formedsubstrate.

There are some important parameters involved in the above-describedmethod. Thus, the thickness of the substrate material must be at least0.020 inches. Also, the ink used in the process is a formable, hightemperature ink that can withstand the stresses of the form as well asthe heat from the injection of molten resin during the in-moldingprocess. Furthermore, the molding tools face (area where the front ofthe applique rests on the tool) should be maintained at a temperature of70°-110 ° F. Further, the resin itself should not exceed 700 ° F.

A feature of the method in accordance with the invention is that thepolycarbonate resin is injected through gates directly onto, andperpendicular to the surface of the applique. Further, each individualgate supplies molten polycarbonate resin to an area in the mold which isno greater than two square inches.

An important advantage of the method of the invention is that it iscapable of producing a three dimensional shaped product which has,therefore, not been done. Further, the use of cold forming and thesubsequent injection molding process makes it possible to produce aproduct with a reduced amount of internal stress. The prior art methodscannot achieve this result. Further, the prior art, such as U.S. Pat.No. 4,917,927, has not considered it possible to inject directly ontothe printed applique substrate because of concern that the molten resin,with its high temperatures and heat, will destroy the applique. However,with the method in accordance with the invention wherein the gatessupply ah area not exceeding two square inches, it is possible to reducethe process heat and pressures and still inject directly onto theapplique. The advantage of injecting directly is that it is possible toprotect the flow of the molten resin and not have to force it into areasby increasing the pressure. The novel gating arrangement also makes itpossible to design the mold with greater ease in that there is norestriction that the gates be located so as to prevent material fromimpinging upon the applique surface in a fashion that would disrupt theapplique. Also, by pre-forming the printed applique substrate andproviding a molding tool as described above, there is no need to use themolding pressures to create a product having a three dimensionalconfiguration.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational view of a molded applique product made bythe method in accordance with the invention.

FIG. 2 is a section taken on line 2--2 of FIG. 1.

FIG. 2a is an enlarged detailed view of the circled portion shown inFIG. 2.

FIG. 3 is a plan view of a printed substrate pursuant to the method inaccordance with the invention.

FIG. 4 is a perspective view of a formed substrate pursuant to themethod of the invention.

FIG. 5 is a perspective view illustrating the molding step pursuant tothe method in accordance with the invention.

FIG. 6 is a diagramatic view of the molding step shown in FIG. 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An initial step in accordance with the method of the invention is toprovide a flat substrate having a minimum thickness of 0.020 inches andbeing made of a clear polycarbonate, such as "Mylar". The substrate isindicated generally at 10 in FIG. 3, for example.

The next step in the method is to print the desired design on the frontsurface 12 of substrate 10 using formable ink. As shown in FIG. 3, aprinted design indicated generally at 14 is provided in a rectangularconfiguration. The printing step is performed by the making of aplurality of printing passes wherein a single color is applied duringthe running of each path. The different colors are also applied in thecircular areas shown in FIG. 3 located above the printed design 14,which areas 16 form no part of the completed product as will bedescribed hereafter. Also, a plurality of marks 18 for registrationholes are printed at locations located around the printed design 14 asis apparent in FIG. 3.

The next step is the shearing step wherein the printed substrate 10 isprecut into rectangles and has a plurality of registration holes (atmarks 18) punched therein. This step produces a printed part that isprepared to be used in a forming tool whereby it is shaped to fit withinthe tool and to register with the registration pins of said tool. Thisstep is preferably performed by die cutting with a steel rule die.

The next step is the forming step wherein the precut printed substrateis formed into a three-dimensional shape, such as the formed substrate20 illustrated in FIG. 4. The forming step is preferably performed by acold forming process to thereby reduce the internal stress from theinternal form. In this step, the flat sheet is placed into a formingpress which is run through its forming cycle to form the sheet into thethree-dimensional shape desired, which shape can have, as illustrated inFIG. 4, a bent configuration including protruding portions or concaveportions.

The next step is to cut the formed substrate 20 into a configurationsuch that it fits into the die used in the molding step to be performedhereafter in a manner that the configuration of the formed substrate 20serves to hold it in place. Thus, the formed substrate 20 must by cut sothat it fits into the molding tool with a minimal interference fit.

In FIG. 5, there is shown a molding tool 30 for use in the method inaccordance with the invention. The molding tool 30 provides a cavity 32which includes a first surface 34 that has the same configuration asthat of the formed substrate 20. The molding tool 30 is formed of afront half 36 and a back half 38 which are secured together to definethe mold cavity 32 therebetween. The back mold half 38 is provided withthree gates 41, 42, and 43 through which the molten material isintroduced into the bottom of the cavity 32. The three gates 41, 42, and43 extend in a direction perpendicular to the mold cavity 32. Moreover,as is best shown in FIG. 6, the molding tool 30 is constructed andarranged so that each gate does not supply molten resin to an area ofthe mold cavity 32 greater than two square inches.

The next step in the method is the insert molding step wherein theformed substrate 20 is placed into the cavity 32 of the molding tool 30against the front mold surface 34 in a position as illustrated in FIG.5. After this, a clear molten polycarbonate resin is injected into themold cavity space located behind the formed substrate. This step isachieved by introducing the molten polycarbonate in the bottom of cavity32 directly behind the formed substrate through the three gates 41, 42,and 43 constructed and arranged in the manner as described above so thateach gate 41, 42 or 43 does not supply molten resin to an area of moldcavity 32 greater than two square inches. FIG. 6 illustrates the flow ofthe molten resin upwardly within cavity 32.

The above-described method produces a one-piece permanently bondedapplique product having the three dimensional shaped configuration ofthe formed substrate 20 as is apparent from FIGS. 1 and 2 whichillustrates the molded-applique product 50. Thus, the product 50comprises a front wall comprising formed substrate 20, which includes aplurality of printed layers 52 which are applied to the front face 12 ofthe substrate 10, and a back wall comprising the clear polycarbonateresin substrate 54.

EXAMPLE

The parts were printed, seven-up, on a 22 inch by 31 inch, 0.020 inchthick polycarbonate sheet, all printing being a front surface operation.Below is a list of the passes and the specifications for running thesepasses:

    ______________________________________                                                         DRY             EMUL-                                        PASS    INK      TIME    SCREEN  SION   BLADE                                 ______________________________________                                        1. Pinhole                                                                            40070306 3.5 hrs.                                                                              270 Wire                                                                              Direct 85 D.                                         Mylar                           Sharp                                 2. Green                                                                              40070271 3.0 hrs.                                                                              270 Wire                                                                              Direct 85 D.                                         Mylar                           Sharp                                 3. White                                                                              40070307 3.0 hrs.                                                                              270 Wire                                                                              Direct 85 D.                                         Mylar                           Sharp                                 4. Yellow                                                                             40070313 3.5 hrs.                                                                              270 Wire                                                                              Direct 85 D.                                         Mylar                           Sharp                                 5. Red  40070314 3.5 hrs.                                                                              270 Wire                                                                              Direct 85 D.                                         Mylar                           Sharp                                 6. Blue 40070317 3.5 hrs.                                                                              270 Wire                                                                              Direct 85 D.                                         Mylar                           Sharp                                 7. Graphics                                                                           40070306 3.5 hrs.                                                                              270 Wire                                                                              Indirect/                                                                            85 D.                                         Mylar                    Direct Sharp                                 ______________________________________                                    

After printing, the parts were sheared into rectangles for use in a onecavity forming tool. Registration holes were punched in the parts atthis time also, whereby the parts were ready for the forming press.

The forming step was performed in a one cavity tool. Each part wasplaced on the tool's registration pins by inserting the pins within theregistration holes previously punched therein and the part was thenformed. The forming procedure involved the following steps:

1. The tool was placed on the shuttle table that enters the press.

2. A "slow-close" technique was used to set the machine to theconfiguration of the tool.

3. Pressures were then set to 4,000 pounds.

4. Parts were then placed on the tool using the registration pinsestablished.

5. The parts were then run through the forming cycle two times and thenremoved.

In the next step, i.e., the cutting step, the parts were lazer cut to adesired size so as to fit properly in the molding tool.

After cutting, the parts were placed by hand into the molding tool, withthe configuration of the form serving to hold the part in place. Cautionwas taken that the part sits flush with the forming tool. The head ofthe tool whereat the applique sits was cooled to 70° F. using coolinglines and the molten polycarbonate was set to 700° F. at 500 psi. Thepolycarbonate was then injected into the mold cavity behind the printedpart. During operation, the pressures and temperatures in the moldingprocess were held as low as possible to reduce the chances of the inkrunning.

The part was then removed from the die and masked in the back thereof atall locations with the exception of the graphic areas. This reduced thepossibility of pin holes.

After the parts were masked, they were spray coated to provide a coatingthereon for anti-scratch and solvent resistiveness. The part was thenexamined for suitability for shipment.

What is claimed is:
 1. A method of making applique products of the typemade of synthetic resins and having printing thereon by a moldingprocess to produce a three dimensional product having a shape includingprotruding portions or concave portions comprising the steps of:(1)providing a flat substrate having a minimum of 0.020 inches thickness,said substrate being made of a synthetic resin, (2) printing on a frontsurface of said substrate using a formable ink, (3) preparing theprinted substrate for forming, (4) forming the printed substrate into athree dimensional shape having a front surface and a back surface, (5)providing a mold having a cavity including a mold surface of the sameconfiguration as the front surface of said formed substrate, (6)preparing the formed substrate to have dimensions such that it fits intothe mold cavity in a secure position with said front surface of saidformed substrate in contact with said mold surface, (7) placing theformed substrate into the cavity of the mold in a secure position withsaid front surface of said formed substrate in contact with said moldsurface and closing the mold in preparation for a molding operation,and, after the completion of steps (1) to (7), (8) injecting a moltenresin into the cavity space located adjacent said back surface of saidformed substrate at locations so the resin flows directly onto theformed substrate through a plurality of gates, said gates beingconstructed and arranged so that each gate does not supply molten resinto an area of the mold cavity greater than a predetermined area so as toreduce internal stress in the applique product produced, wherein step(4) is performed by a cold forming process to thereby reduce internalstress produced in the formed substrate, wherein step (6) of preparingthe formed substrate is performed by die-cutting the formed substrate ina manner such that it is dimensioned to be placed into the mold with aminimal interference fit, wherein said flat substrate of step (1) is aclear polycarbonate and said molten resin of step (7) is made of a clearmolten polycarbonate resin, wherein said formable ink is a hightemperature ink that can withstand the stresses of the forming step aswell as the heat from the injection of molten resin, wherein said moldsurface is maintained at a temperature of 70°-110° F. and the moltenresin temperature does not exceed 700° F., and wherein said molten resinis injected through gates directly onto and perpendicular to the backsurface of the formed substrate placed in the mold in step (7).
 2. Themethod according to claim 1 wherein each gate does not supply moltenresin to an area of the mold cavity greater than two square inches. 3.The method according to claim 1 wherein step (3) of preparing thesubstrate for forming is performed by precutting the printed substrateto establish registration holes for forming by means of a cutting stepperformed by die-cutting with a steel rule die.